WASHINGTON -- U.S. Sen. John Barrasso and other Republicans boycotted the start of committee debate Tuesday on a bill to curb greenhouse gases, protesting that the bill's costs have not been fully examined.

Republican Sen. George Voinovich of Ohio attended the session for 15 minutes to explain the GOP's argument for staying away. He insisted the tactic "is not a ruse" to block the bill, but concern that its widespread impact on the country has not been made clear.

Barrasso, in a phone interview with the Star-Tribune on Tuesday, said he needs to see an EPA analysis of the impacts of the legislation and data from the Congressional Budget Office regarding costs before he's willing to begin debate.

"To me, the fairness of what we're asking for is overwhelming," Barrasso said. "This is something that really deserves discussion and debate."

But Sen. Barbara Boxer of California, the panel's chairwoman, argued the EPA already has provided "a full blown economic analysis" and that Majority Leader Harry Reid has promised further studies when the bill is merged with other legislation. She insisted, "We're not rushing. We are taking our time."

The partisan rift in the Environment and Public Works Committee, which delayed votes on amendments to the legislation, exposed the sharp divisions in the Senate over how to address global warming. Democrats also have been split on the issue. Sen. Max Baucus, D-Mont., who said he had deep reservations about the bill, also was absent.

Boxer had hoped to push the legislation out of her committee this week, so it could be merged with provisions from five other committees and demonstrate to the world some progress in Congress before the international climate conference begins in Copenhagen, Denmark, in December.

President Barack Obama has repeatedly called on Congress to pass climate legislation. But the issue has become bogged down in the Senate over strong opposition from Republicans -- and some Democrats as well -- who fear the loss of jobs and higher energy prices.

"There are bipartisan concerns about what's being proposed here," Barrasso said. "People understand it would have a dramatic effect in a negative way on our economy."

The Democratic bill calls for cutting greenhouse gas emissions from power plants and industrial facilities 20 percent by 2020 and 83 percent by mid-century. Polluters would be given pollution permits that they could trade among themselves to ease the economic effect of the transition from fossil fuels.

"This is not a ruse to prevent this committee from marking up a climate bill. Rather this is a genuine attempt ... to have the best information available as we debate and amend the bill that will have consequences for every person in the country," said Voinovich whose state is especially vulnerable because of its reliance on coal and manufacturing base. He said an analysis by the EPA cited by Boxer was inadequate, made "unrealistic assumptions" and was based on a House-passed bill that he said is significantly different from the bill before the Senate panel.

But Boxer disagreed and said the bill she has co-authored along with Sen. John Kerry, D-Mass., was "90 percent the same" as the House version that has been fully examined by the EPA. That EPA analysis estimates modest cost to households from higher energy prices of $80 to $111 a year.

"There is no reason at all for additional analysis and spend more taxpayer dollars doing it when the work has been done," said Boxer. She called the GOP boycott a delaying tactic and promised, "we're going to be here every day until they join us."

Democrats have a 12-7 majority in the committee and enough votes to advance the measure. But an attempt by Boxer to ram the bill through committee without Republican participation could backfire when the measure gets to the floor where it will be combined with other climate legislation.

On Monday, the ranking Republicans on five other committees that will have some say in climate legislation also called the EPA analysis unsatisfactory and said senators should not be expected to vote on a bill "without a full and complete analysis of the likely effects." They warned in a letter to Boxer that failure to accommodate GOP senators seeking further studies "would severely damage rather than help" the chances of getting the bipartisan support needed to get a bill through the Senate.